Why can't commercial airplanes seem to get it together when it comes to a comfortable temperature in the cabin?
Travelers' frequent lament is the complexity of dressing for flights — because airports are often freezing, and planes are typically overheated before takeoff... then plunge to arctic temps once the air kicks on. So, the unanswered question among travelers is, "Why is it so hard to settle on a moderate, comfortable temperature?" Like most apparent mysteries about airplanes, there are answers to that.
According to retired Delta captain Paul Eschenfelder cited in Traveller, the older the aircraft, the more likely you are to freeze on board. New airplanes can regulate temperature in different areas of the cabin quite precisely (even down to the row), but older flights can't, and have to use the same temperature throughout the cabin.
That means, some areas need the air conditioning levels higher for passengers to even feel it, while other people are getting blasted with cold.
It doesn't hurt to ask the flight attendant to change the temperature — just be polite, for the love of god — and on new aircrafts they actually can.
Jezebel noted, "If you are able to select your seats in advance of your flight, make sure you’re at least two rows away from any exit doors — sometimes they’re not a problem, but sometimes they’re painfully drafty — and try to avoid the very back of the plane, where it’s a little colder."
Most experts agree that extreme temperatures on airplanes, and even within airports, are largely unavoidable. So the best thing to do is pack for it. That means layers. According to Traveller: "Crew members say they'll try to make your trip as comfortable as possible. But at a time of year when outside weather can be intense, and when the aging infrastructure isn't enough to protect you, cabin comfort is your responsibility."
For long-haul flights consider leggings or some appropriately sophisticated alternative to sweatpants, with a T-shirt and lightweight sweater layered up on top. Bring along that all-important sarong or shawl, which both serves as a much-appreciated extra layer on the plane, as well as a multifunction packing essential at your destination. Definitely bring socks. (If you're headed somewhere tropical, make sure you have a lightweight change of clothes in your carryon so you're comfortable when you step out in the blazing sun.)
Then, when you get on the plane, request an extra blanket from the flight attendant. You'd be surprised how much you can get on planes when you simply ask!